Single Webers.. Anyone run this set up?

[Zach Gomulka]

Yes, simple port and valve job will go a long way. Engle 100 will be plenty, although I'm sure you'll find people who disagree. I prefer not to over cam small engines, especially when using a single carb.

[Lids]

i ran a single carb and fitted one of those heater blanket things, it was fine even in winter

[plasticblack]

Yes, simple port and valve job will go a long way. Engle 100 will be plenty, although I'm sure you'll find people who disagree. I prefer not to over cam small engines, especially when using a single carb.

Agreed, I'd rather have a really useable set up, that can be used everyday? Do you have any thoughts on a Lightened Flywheel added into the mix?

Am I right in thinking the Flywheel will lose me some top end performance but help with take off 

This is type of Manifold I'm looking for.
  http://www.thesamba.com/vw/classifieds/detail.php?id=1409760

[Zach Gomulka]

Counterweighted crank and a light flywheel. Standard lightened flywheel is 12.5 pounds. Super light flywheels can sometimes make it tricky to get going smoothly from a stop.
The carburetor you want is a PO10 (sometimes just marked PO), that is for a single carb application. There are also PO3(R&L) and PO19(R&L). The R&L is right and left, for Porsche dual application. The jetting is different as well as the throttle plate and of course the linkage arm.
With the PO10 carb you want an individual runner manifold, NOT a plenum style. The one you pictured is the correct style, but I don't have any experience with that style manifold specifically- the one I used retained the factory VW end castings, which I prefer.

[plasticblack]

Good info again Zach Thanks...

I'll make sure I get the right PO10 type carb. 

[youngnstudly]

You can see in the link below what I'm talking about with the manifold being setup for better throttle cable alignment. If you look at the carb and manifold base, it appears as if someone grabbed the base and "twisted" it clockwise (like tightening a lid on a jar) before it was welded together. From what I can tell, some of the more popular bugspray manifolds come with that "twist" in the flange already, but I don't know if the they have the same bolt pattern as a Zenith or not.   

http://www.thesamba.com/vw/forum/viewtopic.php?t=466289&highlight=bugspray++zenith

http://www.thesamba.com/vw/forum/viewtopic.php?t=423070&highlight=bugspray++zenith

I've heard both arguments about the Zenith single needing a plenum manifold or an isolated manifold with the PO10 model carb, but I also notice that a lot of PO10 carbs don't have the slot in the throttle plate base. That leads me to believe someone has swapped bases in order to get one that didn't have loose throttle shaft bushings. I will probably experiment with my manifold setup and see what works best. It's my understanding that if the throttle plate base has the slot connecting both bbls., you can run the isolated manifold. If not, you must run the plenum style manifold.

Zach is right about using a small aftermarket cam (like the Engle 100) over the stock cam with 1.25 rockers, but with my case (pun intended) I didn't want to split the bottom end open just to replace the cam. The engine only had 45,000 miles on it so I just did the top end and added a few upgrades like the 1.25 rockers, headwork, and Kadrons (for now). More head work, larger valves, and more displacement will all allow you to run a slightly "bigger" camshaft with little or no ill effects other than high idle speed when using a single carb. Don't go overboard though!

As for the lightened flywheel, I can't say one way or the other with a single carb application since I am treating my engine as if it were stock (with a little more power). On all of my performance engines with dual carbs, I have always run with a 12lb flywheel and a CW crank, which does rev a little faster (although the Counterweights offset the lightened flywheel). With a bigger camshaft, a stock heavy flywheel can help smooth out the rough idle a little bit though. 

Andy

[plasticblack]

Thanks for the links Andy.

Lots of very helpful information and especially regarding the Zenith Base Plate issue.

I'm undecided about the Lightened Flywheel and need to be sure of the positives & negatives at the top and bottom end of performance.

I'm not planning any upgrades such as twin carbs or anything. I want a particular look and twin carbs don't meet my requirements. 

The slot issue is the same for the Holley Bugspray set up regarding manifold choice.

[Zach Gomulka]

The only negative about a lightened flywheel is that if it is lightened too much it may be difficult to keep the revs up from a dead stop. This effect is compounded if you have an engine that makes very little low rpm torque, the combo I suggested will be very torquey off the line and pull well to about 5k rpm. You won't have that issue with a 12.5lb flywheel (I believe a stock flywheel is about 17-18lbs?). A counter weighted crank ads about 3 pounds. A lightened flywheel will get to the power much quicker and be much more entertaining to drive. I wouldn't personally build any engine without a c/w crank and a lightened flywheel, even if the rest of it is 100% stock.

[plasticblack]

The only negative about a lightened flywheel is that if it is lightened too much it may be difficult to keep the revs up from a dead stop. This effect is compounded if you have an engine that makes very little low rpm torque, the combo I suggested will be very torquey off the line and pull well to about 5k rpm. You won't have that issue with a 12.5lb flywheel (I believe a stock flywheel is about 17-18lbs?). A counter weighted crank ads about 3 pounds. A lightened flywheel will get to the power much quicker and be much more entertaining to drive. I wouldn't personally build any engine without a c/w crank and a lightened flywheel, even if the rest of it is 100% stock.

I wasn't planning on the c/w crank and will have to think seriously about this. It's a few £100's more but perhaps well spent.

My initial aim was to buy an off-the-shelf 1600 engine and go from there... Perhaps I'm going to have to spend the extra to have all the internals just right...

[Zach Gomulka]

If smoothness and longevity is a concern, it's the way to go. I wouldn't lighten the flywheel with a stock crank.

[plasticblack]

If smoothness and longevity is a concern, it's the way to go. I wouldn't lighten the flywheel with a stock crank.

I'll have to re think the engine budget a liitle and make sure that it's going to last.

[Lee.C]

NOTHING beat a nice counterweighted crank and fully balanced bottom end - Such a noticeable difference 

[plasticblack]

At present all my engine plans are up in the air, but I have an outline and have gained a massive amount of good information from this thread.

Thanks All.. 

[fish]

I had a 1776 with stock balanced crank, lightened flywheel, stock ported heads, AP3 cam, stock lifters, stock pushrods, twin 36 IDF webers
pulled 74 hp atw, same combo with 6.5 psi 94 hp atw.

[modnrod]

I've had a few single carb streeters.
1641, stock cam and 1.4 rockers (didn't split the cases), ported 355A TP heads, Solex 34 and custom centrebranch into stock end-pieces, cheap crappy 4-1 and hotdog........mid-15s with 1300 gearbox pushing 850kg. I reckon that's a good result for a daily driver. An upgrade to an Engle 100 and 1.25 rockers gained less than 2 tenths, so unless your cases are already split, for a mild combo like this I wouldn't bother camming it up. Engle 110 MIGHT give you an extra 5HP, but you WILL lose grunt under 2500-3000.
Single carb streeters work well, but yes, when it gets below 5*C they get a bit ugly without heat. You can use hot exhaust air into air filter like stock, heated manifold like stock, I've even seen copper tubing holding engine oil wrapped around a single SU carb manifold in an older Type 3 which worked fine for pre-heat. It won't adversely affect performance more than a few HP, even in 45*C, but you will gain a good 10-15% fuel economy everywhere, and really nice driveability. If your temps are always over 20*C you can easily live without the pre-heat though.

That's what I've found anyway over the years.

[plasticblack]

I'm still hoping that I can put together the single carb set up with either a Zenith or Weber DCN.

 It does look though as if the engine is going to make this a longer project than I had first thought....

[Lee.C]

I'm still hoping that I can put together the single carb set up with either a Zenith or Weber DCN.

 It does look though as if the engine is going to make this a longer project than I had first thought....

i still got that NOS dcn